Booster for lens edge grinding machines



Nov. 18, 1952 E. M. LONG BOOSTER FOR LENS EDGE GRINDING'MACHINES Filed Oct. 6; 1950 2 SHEETS-SHEET l EU M. LONG INVENTOR 8% a fi ATTORNEY Nov. 18, 1952 E. M. LONG- BOOSTER FOR LENS'EDGE GRINDING MACHINES Filed Oct. 6. 1950 '2 SHEETS-SHEET '2 ELI NI. Lone ATTORNEY Patented Nov. 18, 1952 UNITED STATES :PATEN T OFFICE jBOOSTER .FOR LENS. EDGE: GRINDING MACHINES Eli 'M. "Long, Alamogordo, 'N; .Mex., assignor to Shuron Optical Company Inc 'Geneva', "N. Y..

acorporation o'f New York Applicationflctober 6, 19 50, Serial'No.*188,710

lcoaxially with lthe'lens to rotate with the chuck.

A stop-device, or shoe, 'is adjustabl'y fixediin relation'to thegrinding wheel soas'to be contacted hy'ithe .edge of 'thersizer to limit'the travel of the chucktoward'the "grinding wheel "as the edge of "the lens is ground away. "Since the lenses required bymostfophthalmic mountings today are of'irregular shape, some portions of .the'perimeter of the lensrequire-moregrinding, and hence longer "contact/with the grinding -wh'eel, than others. This'is due'to the fact that the flatter portions of the periphery present=longer arcs-of contact with thegrindingwheel 'than the more convex portions.

'Attaehmentswcalled boosters, designed to de- \crease the grinding time in :such machines in the-past have be'en either of the intermittent or of-the variable :speed type. Attachments of the intermittent type provide :means for stopping the rritation of the lens until thezsizer comes into ocontact with :its shoe, whereupon the lens .is :ro-

:tatedijustizfar enough to zpresent ia new; unigmundzportion 10f. thesperime'ter tozthe grinding n-wheel. With -this .astarteSt-Op type of. device, .;the dens isground: down to substantially .the shape required in :one-acomplete revolution of the :lens.

,aAttachments of the variablespeed type. doxnot attempt to grind'down the {edge-of the lens to the required limit 'inone revolution of -the lens, but providemeans-for speeding up the rotation of the lens whenever the sizer comes into contact with .-.its;shoe. The-hereindescribed'i-nventionis of this slow-fast type, which ;is superior to the. startnecessitateatemporaryfinterruption of the transmission of rotary motion to the lens while the shift in gearsis'made.

The'booster which is the subject of the present invention, speeds .uplthe rotation of the lens by means of .an auxiliarymotor operating upon one of the gears of a. difierentia'lhgeartrainiwhichis normally. prevented 'from rotating 'by reason of the construction of the gearing. This motor is .energizedby means of a micro-switchiwhen Lthe sizer comes into contact with its shoe. and is deenergized when an unfinished part oftheedge of the lens comes into contact with the grinding wheel. p A novelbraking device on the motor insures the immediate. stopping of the motor, v-upon its-being de-energized.

Such construction insures that rotary motion is continuously transmitted to the lens so that .the edge of the .lens will be continuously and smoothly ground away to thedesiredsize.

One of the principal objects of the-inventionis to provide means whereby the timensually required for edging a lens is reduced,

Another object is to provideautomatic means for increasing the speed of rotation "of .sthe:.lens

iwhilezfinished portions of the .edgeoii'athe lenssare adjacent the grinding wheel.

'Another obiect is to :provide positive drive means for rotating the lens and means for inacreasin'g the speed 'o'fs-rotation of the lens without interrupting the pos'itive connection between the power source and the rotating lens.

A further object is to provide means forum- .media-tely-decreasingthe speed of rotation of'the lens "when" an unfinished portion of the-perimeter of the lens is presented to the grinding wheel.

A still further object is to provide an :attachment whieh'may be easily connected to ianj'edging machine to increaseits efiicienoy.

"Other objects and advantages offthe present invention will be apparent'from theffollowingidescription taken "in conjunction with the accompanying drawings, in which:

Figure 1.15 a .side elevational view of va lens edging machine with the attachment connected thereto;

. Figurez is .aitop plan thereof;

.Figure .3 .is an enlarged, fragmentary; side- ,elevational view of the "sizer switch and-adjacent parts of the attachment, with a portion 01' of the attachment and adjacentgparts, partly in section on the line 6-6 of Figure 8, and with a portion of the motor housing broken away to show the motor brake;

Figure 7 is a sectional view on the line 1-1 of Figure 8;

Figure 8 is a fragmentary top plan of the attachment, partly in section on the line 8-8 of Figure 6;

Figure 9 is a sectional view of the planetary gearing on the line 39 of Figure 6; and

Figure is a side-elevational view of the planetary gear support of Figure 9.

Referring more particularly to the drawings, an edging machine It], as shown in Figures 1 and 2, which is more fully described in my United States Patent No. 1,272,474, comprises a grinding wheel H mounted on a shaft I2 which is supported in suitable bearings I3 secured to a base IL, Base I4 is adapted for mounting on a bench or stand and is in the form of a trough containing the lower portion of the wheel I I and having side flanges l5 and an upwardly and forwardly inclined guideway It at the front. On guideway I6 is adjustably secured a movable section H for receiving and supporting the sliding carriage [8. A shield l9 encloses the rear portion of the wheel II.

To one end of shaft 22 is secured a pulley 28 (Figure 2) connected to a motor, not shown, .by

which grinding wheel I I may be rotated. To the other end of shaft i2 is secured a pulley 21 which drives pulley 22 by means of a belt 23. Pulley 22 is secured to a shaft 24 mounted transversely in the front portion of base [4 in suitable bearings and which operates a hydraulic mechanism, not shown, which reciprocates carriage l8 transversely of the machine. The extent of the reciprocatory motion of carriage I8 is adjustable by means of the screws 25.

Carriage I8 is provided at its opposite ends with upwardly and rearwardly extending arms 26, to the upper ends of which is pivotally secured the lens chuck frame 21, said frame being thus oscillatable toward and away from the grinding wheel. Secured to one end of frame 21 above its axis of movement is an extension 28 in which is journaled the lens chuck drive shaft 29 to which rotary motion is transmitted from the grinding wheel shaft 12 through pulleys 2| and 22 and shaft 24 as follows:

Shaft 24 projects from base l4 through a cylindrical boss 24' (Figures '7 and 8) and extends beyond pulley 22. Near this end of shaft and exterior to pulley 22 is secured a worm 36 (Figure 6) which, by means of gearing hereinafter described, transmits rotary motion to the flexible shaft 3|, the upper end of which is provided with a spiral gear 32 meshing with a similar spiral gear 33 on the shaft 29;

, The upper end of flexible shaft 3| is journaled in a yoke 34 which is pivotally secured to an arm 26 by screw-stud 35. The yoke 34 is journaled on an eccentric portion of a rock shaft 35 having may be independently rotated.

The lens chuck frame 21 best seen in Figure 2, comprises an upper portion 40 which houses a transverse shaft, not shown, connected to rotate with the lens chuck drive shaft 29, side portions M and 42, and a lower lens chuck portion 43, comprising a pair of coaxial lens clamping members 44 and 45 arranged end to end and having their adjacent ends provided with suitable pads shaft housed in portion 48, so that each spindle is 1 driven at the same rate.

Lens clamp 45 and its spindle 43 are retractable away from clamp 24 by means of lever 50 and mechanism, not shown, housed in portion 42 of the lens chuck frame, so that lenses may be easily and quickly clamped in the machine. Between lens clamp 44 and its spindle 41 is the pattern or sizer 5| secured to rotate therewith and easily removable therefrom by means of mechanism not shown. Spindles 41 and 48 thus operatively form a single work spindle.

A sizer shoe 52 (Figures 2 and 3) is secured to slide I8 adjacent the side of grinding wheel H by mechanism hereinafter described. It is adjustable, by means of the adjusting wheel 53, toward and away from the axis of rotation of the rinding wheel II and is located in the path of sizer 5! on the lens holding frame 21 as said frame is swung toward grinding wheel I I, acting as a stop to prevent grinding away more than the required amount at the end of the lens 46.

A hone 54 (Figure 2) for truing the grinding wheel is also carried by slide l8.

Mechanism to rock frame 2! with its attached lens 36 toward the grinding wheel I l is provided in the form of lever 55 (Figures 1 and 2) pivoted at 56 to the shield is. A forwardly and rearwardly extending guide 51 on lever 55 is provided with an adjustably mounted weight 58 thereon, the latter being held in its adjusted position by a set screw 59. Lever 55 is provided with a downwardly projecting arm 6%! connected by a link 6| to frame 21 below its axis of swing.

The lens edge grinding machine It) thus far. described constitutes the setting of the present invention, rather than the invention itself, and is already known to the art through commercial edge grinders manufactured under said Long Patent 1,272,474. The foregoing description is therefore believed to be ample for the understanding of this invention, the features of which will now be described in greater detail.

The booster attachment which is the subject of the present invention is shown in Figures 1 and 2 and comprises an auxiliary motor 65, certain gears in a gear box 66, a sizer switch mechanism Bl and certain electrical wiring and an electri cal junction box 68.

The gear box or casing 66 is best shown in Figures 7 and 8 mounted on shaft 24 outside of pulley 22 and has an arm 69 which extends around the other side of pulley 22 and clamps on boss 24 by means of clamping screw Ill. The gear box 63 may be adjusted to the proper angle by the jack screw H which projects downward from arm 69 and rests on the side flange l5 of r 5 the machine I9. A suitable bearing 12 (Figure 1) is provided for the end of shaft 24.

As best seen in Figures 6 and 8, a worm gear 13, mating with the worm 39 is mounted on, and secured to, a shaft 14 at right angles to shaft 24. Suitable supporting bearings I5 and I6 for shaft 24 are provided in gear box 66, and a spur gear 11 is formed integrally on shaft I4 as shown, keyed thereto, within gear box 66.

On a parallel countershaft 18, shown as a stub shaft secured to casing 66 by a screw I9, is another spur gear 89 in constant mesh with the ear I1.

Another parallel shaft 8| is j ournalled in casing 66 at 82 and 83, and has a tubular planetary gear support member 84 rotatably mounted thereon. To the upper end of member 84 is keyed the spur gear 85 in constant mesh with gear 89. An arm 86 projects radially from the lower end of member 84 (Figures 9 and 10) and, joined thereto, is a yoke portion 81 on which is mounted a planetary gear shaft 88 parallel with shaft 8| and secured by set screw 89. On shaft 88, between the arms of yoke 81. are rotatably mounted the planetary gears 99 and 9| which are interlocked, as shown, to rotate together.

The lower planetary gear 9| is in constant mesh with a driven sun gear 92 keyed to shaft 8| below member 84. The upper planetary gear 99 is in constant mesh with another, or driver, sun gear 93 rotatably mounted on the tubular portion of member 84. Gears 93 and 99, and gears 92 and 9|, respectively, have different numbers of teeth for reasons which will hereinafter appear. In the particular embodiment shown, gears 9| and 93 each have 1'? teeth and gears 99 and 92 each have 18 teeth.

A large spur gear 95 is mounted coaxially on the driver gear 93 and is joined thereto by means of pins 94, and is in constant mesh with the gear 96. Gear 96 is keyed to the shaft 91 which is parallel to shafts 8|, I8 and I4 and journalled in casing 66 at 98 and 99.

Keyed to shaft 8|, about member 84,- another spur gear I99 is mounted in constant mesh with the gear I 9| which, in turn, is rotatably mounted on countershaft 18 above gear 89. Gear |9| is also in constant mesh with a gear I92 which is shown as coaxially mounted by means of an integral stub shaft I93 borne in a bored hole in the end of shaft I4. Gear I92 is formed with a suitable socket therein for operatively receiving the lower end of the flexible shaft 3|, and is also journalled in casing 66 at I94. A dust cap I95 and oil seal I 96 may be provided about the lower end of the shaft 3|.

Casing 66 is preferably formed in two parts, as best shown in Figure 6, the upper part 9 being joined to the lower part I II by screws H2. The interior may be filled with oil to a suitable level, a filler plug 3 being provided at the top and a drain plug H4 at the bottom.

The auxiliary electric motor 65 is secured to casing 66 by screws and the armature shaft |I6 thereof extends into the interior of the casing and is journalled therein at III and H8 so as to be parallel with shafts 91, 8|, I8 and I4. Keyed to the motor shaft I I6 is a worm I29 which is in constant mesh with the mating worm gear I 2| on shaft I22. Shaft I22 extends across the casing 66 perpendicular to shaft I I6, and is journalled at I23 and I24 in suitable manner. Worm gear. I2I is keyed to shaft I22 as is the worm I25 thereon which is in constant mesh with the mating worm gear I26 which is keyed to the re duced upper portion of shaft 91 above gear 96.

Motor 65 is provided with a fan I39 (Figures 5 and 6) which is secured to a metal brake disk |3I by screws I32. Disk |3I is secured to shaft II6 by a set screw I33 so as to provide end play in the shaft 6 on the rder of .915 inch for reasons which will hereinafter become apparent.

To the main body of motor 65 which contains the usual field coils, is secured a metal ring I34 by screws I35. To the upper surface of ring I34 is cemented a leather brake ring I36 with any suitable adhesive, the upper surface of ring I34 and the lower surface of brake disk I3| being parallel and in planes normal to the axis of shaft I|6.

Shaft H6 is provided with the usual armature, and a housing I3'I with a suitable ventilating cover I38 is provided about the motor being spaced therefrom by longitudinally disposed fins I39 to provide ventilating passages for the fan I39.

The sizer switch 61, as shown in Figures 3 and 4, is supported by the screw I49 which is threaded. into a portion of the reciprocating slide I8 at I4 I and to which the adjusting wheel 53 is secured. The square lower portion of screw I49 has a projecting lug I42 which is guided in slot I43 (Figure 3) of the slide I8 and in which is seated one end of a coil spring I44, the other end of which is seated in a suitable pocket in slide I8. At I45 a yoked switch support bracket I46 is pivotally secured to the screw I49. The extent to which bracket I46 may pivot with respect to screw I49 is limited by means of set screws I41 and I48 which are threaded through screw I49 from opposite directions and contact bracket I46 and thus provide means for adjustably positioning the conventional microswitch I59 which is secured to bracket I46 by bolts I5I. Also secured to bracket I 46 by means of a bolt I52 is the conventional sizer shoe 52.

A switch operating arm I55 is also adjustably positioned on the reduced rounded lower end of screw I49 by means of the clamping bolt I56. A switch operating button I51 is located on arm I 55 so as to contact the microswitch. button I58 and a switch stop I59 is positioned adjacent a suitable portionof switch I59.

A dust cover or housing of aluminum or other light material is provided in two parts I69 and I6I, bolted together at I62 and secured to arm I55 by bolts I63. Suitable openings for projecting: portions of bracket I46 and screw I49 are provided between the portions I69 and |6I of the housing. An insulated cable I64 contains the lead wires connected to the terminals of microswitch I59 and which lead to appropriate terminals in the electrical junction box 68.

Junction box 68 (Figures 1 and 2) is clamped or bolted in any convenient manner to the side flange I5, as by bolts I65, to the rear of pulley 2|. A conventional signal light I66 projects upward from the junction box 68- and is wired. in conventional manner to light up when the sizer 5| is in contact with its shoe 52. The junction box 68 contains the necessary terminals and wiring and is provided with an intake cable I61 containing lead wires adapted to be connected to an electric power source. An insulated cable I68 contains lead wires from the appropriate tergiinals in motor 65 to those within the junction In the operation of the attachment, it will be understood that an unedged lens 46 and an appropriate sizer 5| are placed in the machine I9 w'heel l I. Theslide |8' reciprocatestransversely carrying the lens across theface of the grinding wheel ifl. The lens: 46 is rotated as it rests against the face of the-grinding wheel and-its edge is ground away in the usual manner.

' .ERotationof the lens ifi isaccomplishedas =ro1.- ilowszcPulley 1|, being-secured to the srinding rw heelshaft 1 2, rotate's shaft 24 by means-of belt 23 and pulley-22. "'Toz shaf-t =24 issecuredthe :worm 30, which being inmesh "with the worm gear 13 of the attachment imparts rotary motion to shaft 14 to which it is secured. The-gear 11, being joined to shaft '14, rotates therewith turning the-"spur gears 80-and 85,.gears"|'| and 85'being in constant mesh with gear- '80. Gear 85 is lteyed to the :planetary gearsuppor-t 84- which is therefore rotated about shaft 8| carrying with it the planetary gears 90 and 9|. Gear's!) 'is in constant mesh with the sun gear 93; which is held-stationary 'since it is keyed-to the large gear- 95 which is held stationary by reason of the series of worms and gears connecting the motor shaft H6 to the gear 96 as hereinafter '-more fullydescribed.

Since the driver gear '93 is *held stationary-as the planetary gear 90 is rotated about it, gear 91] is 'forced to rotate-onitsshaft-BB. Gear 8|;bin'g in'terlocked with gear 90,- is forced 'to rotate at =the'same speed. Gears 93 and 90. and 92 and 9|,

respectively, having different numbers of teeth, the driven gear 9 2 is forced to rotate with respect to gear 83 and carries with it shaft 8|.

Since gear Ill!!! is keyed to shaft 8| and since gears H10 and 102 are bothin-constantmeshwith gear gear I02 is rotated, carrying with it the lower 'end of the flexible shaft 3|. This-rotary motion is transmitted through the upper half of the flexible shaft 3| and its'attached spiral gear '32 to the-mating gear '33 attached to shaft "29.

Shaft 29, in turn, drives the spindles 41 and 48 and the lens clamps M and-l of the lens -=chuok through the gearing enclosed in the side portions 4| and 42 of the lens chuck'frame '21 as hereinbefore described.

'When a portion of the edgeoflens Athas'been ground down to the required size; the sizer 5| contacts shoe 52. 'Shoe 52 is secured to the bracket Miwhich carries the switch 150. As sizer 5| presses against shoe 52, bracket I46 is "pivoted Slightlyon its pivot -bo1t-at M5,- thus forcing switch '-|50and its button -against button "I 51 *on'theswitch=operating arm I55; This pressure operates switch i-5o causing the motor 65 to jhe energized.

-Further motion of switch 150-and shoe-52 is prevented when switch 50 comes to rest against the stop 159 on the-operating arm P55. "Shoe 5-2 now becomes a positive step and prevents-size! 151 and lens 46 from swinging toward the grinding- 'w'heel 1|. -Lens- 46 would now be rotated :slowly adjacent, but-out of contact with, wheel M if it were not for the action of motor -65 which will now be described.

'When the pressure o'f-sizer 5| --on shoe -52 operates the switch I50, the motor- 65 energized :and shaft H6. with its attached worm 1 20, caused to rotate. This rotation is transmitted through the worm .gear |2.|,.theashaft I22 and warm I25 to the worm :gear 126; GearsilZ'E and aifiwbeinsskeyed to shaft-9:1, the large spur gear 8 95ymating with geartfigisicausedtwrctate; .The driver sun gear 83 isesecured to :geari ai'andso "rotates with it :causing the-meshing planetary gear-90 to-rota'te at a faster rate on itsssha'ft 88.- "The planetarygear support 84 is still irotating as hereinbefore described and the rotation imparted by motor $5 :is added to that imparted' by the rotation aof shaft 24. Gear S91 being in mesh with gear 92, this increased trotation is imparted lthrough s'haft 8 :gears 1| 00,

NH :and [02 to the fiexiblesh-aft 3| :and thence to the work' spindle 41-48. 'It will be understood from the foregoing that there is no shifting "of gears or interruption of the continuous and edge of -lens lfi is presented' to the grinding wheel As this unfinished portion :comes into contactwith :the'grinding wheel the -'lens chuck frame 21 swung aw-ay from the grinding-wheel and the-sizer 5| -is-'carr-ied with it, removing the pressure on shoe 52. 'When'the pressure on the 'sizer-shoe is removed, it will be-seenthat the vented from-coasting:or-overriding, with anon-- sequent overerotation of 1ens- 48',--bythenovel brake built into the motor, which will now-be described. I

When power is supplied to motor-an inductive force is-set upthe field coils which causes the armature and its shaft 6- to rotate. This same inductive force -also results in a solenoid action familiar to those skilled in the art. The motor armature and shaft 116 arethus lifted up, the-attached brake-disk 3 is-separated from the brake-ring 36 and the motor 65 runs freely. .As :soon .as the :flow of-electricity to 't'he motor '65 is interrupted, however, shaft I Hi with "its attached 'armature drops of itsmwnweightand the brake disk |3| falls against the ibrakezring liafi,

-the friction of::oneagainst the other causinglsubstantially immediate: stopping :of the :rotation of shaft H8.

'It :willbe understood; (therefore, that; whenran unfinished portion of :theedge :of-alens 46 con- .tactsgrinding wheel ,-.sizer 5:| is-withdrawn from its shoe-52, switch 450 "iscturnedbfl and the rotation of motor 6'5 :innnediately-stops; Lens 4.6

now. rotates slowly again, being turned-by shaft .24 as hereinabovedescribed.. This slow-rotation of lens 46 continues until another'finished portion -.of the edgeof the lens is presented to -the grinding wheel when the .motor. 65 1s again ,turnedson and. rapid rotation -.of r lens 46;:again :takes place, This, slow-fast rotationcontinues "untilthe edging .of the lens is completed.

.While the actual speedeo'f rotation of lthelens "comprises no part. of the .present .invention, the approximate speed cfrota'tion .of some of the parts of the-commercial embodiment of machine 1'0; with the attachment'in use, are given hereabove described low speed gear train to drive "the -fiexibl-e shaft '31 at one R. -P. M; Motor 65 c1)- -era'tes at 1700 R. P. and, through the double thread worm 420, the g'four-threadworm l 25, "and the above described high speed "gear train, drives lar'gepgear 95 isheld-stationary when motor 65 isstopped.

The lamp, H56 may. be wired into-the electrical circuits in Well-known manner to light up when sizer is in contact with its shoe 52 and switch ISlI-is turned on. When the lamp is lit continuously, therefore, the operator knows that the edging of the lens is completed.

It will be understood by those familiar with the art that the hereinabove described attachment, comprising sizer switch 61, transmission 66 with the attached motor 65, junction box 63 and the attached wiring, may be easily added to the known edge grinding machine herein described. A flexible shaft 31 is supplied with the attachment which is shorter than that on the commercially known machine heretofore supplied and, on some models, a longer shaft 24 must be installed. It will be apparent that by disengaging the screw at 35, removing the sizer shoe adjusting wheel 53, and sizer shoe supporting mechanism, in wellknown manner, and removing pulley 22 and the yoke supporting the lower end of flexible shaft 3| on the commercially known machine, that the hereinabove described attachment may be easily and quickly installed.

While there is herein described, and in the drawings shown, illustrative embodiments of the invention, it is to be understood that the invention is not'limited thereto, but may comprehend other constructions, arrangement of parts, details and features without departing from the spirit of the invention. I desire to be limited, therefore, only by the scope of the appended claims.

I claim:

1. In a lens edge grinding machine, the combination with a frame, a rotatable grinding wheel journaled in said frame, rotatable means movably mounted on said frame for supporting a lens to be edged by said wheel, a sizer mounted on said supporting means for simultaneous rotation with the lens, means for moving said supporting means with the lens and sizer toward said wheel, and a sizer shoe mounted on said frame for engaging said sizer to limit said movement, of positive drive means for rotating said lens and sizer at slow speed, independent gear- 1 ing means permanently geared to said positive drive means for increasing said speed of lens and sizer rotation when said independent means is driven, and means actuated by the engagemer t and disengagement of the sizer with the sizer shoe for driving and stopping said independent means without interrupting the positive drive of the lens and sizer.

2. In a. lens edge grinding machine, the combination with a frame, a rotatable grinding wheel journaled in said frame, rotatable means movably mounted on said frame for supporting a lens to be edged by said wheel, a sizer mounted on said supporting means for simultaneous rotation with the lens, means for moving said sup- '2 engagement'of thesizer'with the sizer shoe for driving andstopping saidindependent means without interrupting the positive drive of the lens and' sizer.

3; In alens edge, grinding'machine; the combinationwith a'frame, a rotatable grindingwheel journaled .in said frame,; rotatable means mov-- ably mounted on 'said frame for supporting a lens to be edged by-said wheel, a sizer mounted on said supporting means for simultaneous rotation withrthe' lens, means for moving 'said' supporting; means with'thelens and sizer toward saidwheel', and a sizer shoe'mounted on said frame for engaging said sizer to limit said movement, of positive drive. means including differential'gear members for rotating said-lens" and sizer at slow. speed, an auxiliary electric; motor, gearing for driving one of said differential gear. members by said motor'at' increased speed, andswitch means actuated by the engagement and disengagement of the sizer with the sizer shoe for starting and stopping said auxiliary motor.

4. A lens edge grinding machine as claimed in claim 3, in which said auxiliary motor comprises a body provided with field coils and an armature mounted on a substantially vertically extending shaft, said shaft having attached thereto a brake disk, and said body having attached thereto a cooperating brake ring, whereby said motor is stopped substantially immediately upon switching off the electric current thereto.

5. An attachment for a lens edging machine having a frame, a rotatable grinding wheel journaled in said frame, rotatable means movably mounted on said frame for supporting a lens to be edged by said wheel, a sizer mounted on said supporting means for simultaneous rotation with the lens, means for moving said supporting means with the lens and sizer toward said wheel, and a sizer shoe mounted on said frame for engaging said sizer to limit said movement; said attachment comprising positive drive means including differential gear members for rotating said lens and sizer at slow speed, an auxiliary electric motor, gearing for driving one of said differential gear members by said motor at increased speed, and switch means actuated by the engagement and disengagement of the sizer with the sizer shoe for starting and stopping said auxiliary motor when said attachment is in position for use on the lens edging machine.

6. In a lens edge grinding machine, the combination with a frame, a rotatable grinding wheel journaled in said frame, a rotatable support for a lens to be edged movably mounted on said frame, a sizer mounted on said support for simultaneous rotation with the lens, means for moving said support with the lens and sizer toward said wheel, and a sizer shoe mounted on said frame for engaging said sizer to limit said movement, of positive drive means for rotating said lens and sizer, said drive means including differential planetary gears rotatable about a central sun drive gear and a central sun driven gear, means for selectively preventing the rotation of said sun drive gear and for rotating said sun drive gear, and means actuated by the engagement and disengagement of the sizer with the sizer shoe for starting and stopping the rotation of said sun drive gear.

7. In a lens edge grinding machine, the combination with a frame, a rotatable grinding wheel journaled in said frame, rotatable means movably mounted on said frame for supporting a lens to be edged by said Wheel, a sizer coaxially mounted on said supporting means for simultaneous rotation with the lens, means for moving said supporting means with the lens and sizer toward said wheel, and a sizer shoe mounted on said frame for engaging said sizer to limit said movement, of means for rotating said lens and sizer 'operably connecting said grinding wheel and said lens and sizer and including a joined pair of difierential planetary gears meshing, respectively, with a sun drive gear and a sun driven gear, an auxiliary electric motor operably connected for non-reversible rotation of said sun drive gear, and switch means actuated by the engagement and disengagement of the sizer with the sizer shoe for starting and stopping said motor.

8. A lens edge grinding machine as claimed in claim 7 wherein the auxiliary motor comprises a body having field coils and an armature having 12 a substantially vertically mounted shaft, said body having a brake ring secured thereto and said armature shaft having a cooperating brake disk secured thereto, whereby the energization of said field coils serves to lift said disk from said ring during operation of the motor and drops said disk on said ring to stop the motor when the electric current is shut off.

ELI M. LONG.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name 7 Date 2,164,155 Lemay June 2'7, 1939 2,233,312 Harrold Feb. 25, 1941 2,414,126 Sevin Jan. 14, 1947 2,528,137 Grasser Oct. 31, 1950 

